zsh exec format error with empty files

zsh exec format error with empty files

[Christian Neukirchen]

Hi,

It is customary for POSIXy shells that executables which result in
format errors are interpreted as /bin/sh shell scripts.

zsh does this too, but it doesnt work for empty files:

zsh 5.2 (x86_64-unknown-linux-gnu)
zsh-5.2-0-gc86c20a
% ls -l empty colon
-rwxrwxr-x 1 chris users 2 Dec 23 17:53 colon*
-rwxrwxr-x 1 chris users 0 Dec 23 17:49 empty*
% cat colon
:
% ./colon 
% ./empty 
zsh: exec format error: ./empty

For consistency, this should just run /bin/sh as well and return 0,
like in bash, dash, busybox sh, tcsh, mksh, ksh93, posh, Byron's rc
and every tool using execvp.

Happy holidays,
-- 
Christian Neukirchen  <chneukirchen@gmail.com>  http://chneukirchen.org

Re: zsh exec format error with empty files

[Bart Schaefer]

On Dec 23,  6:01pm, Christian Neukirchen wrote:
}
} % ./empty 
} zsh: exec format error: ./empty
} 
} For consistency, this should just run /bin/sh as well and return 0,
} like in bash, dash, busybox sh, tcsh, mksh, ksh93, posh, Byron's rc
} and every tool using execvp.

Hm.


diff --git a/Src/exec.c b/Src/exec.c
index acc867c..c4dc8e3 100644
--- a/Src/exec.c
+++ b/Src/exec.c
@@ -471,9 +471,10 @@ zexecve(char *pth, char **argv, char **newenvp)
 	if ((fd = open(pth, O_RDONLY|O_NOCTTY)) >= 0) {
 	    argv0 = *argv;
 	    *argv = pth;
+	    execvbuf[0] = '\0';
 	    ct = read(fd, execvebuf, POUNDBANGLIMIT);
 	    close(fd);
-	    if (ct > 0) {
+	    if (ct >= 0) {
 		if (execvebuf[0] == '#') {
 		    if (execvebuf[1] == '!') {
 			for (t0 = 0; t0 != ct; t0++)